Synthesis and characterization of mordenite-type zeolites via hydrothermal method using silica gel and sodium aluminate as Si and Al sources at varying temperature

Abstract

Mordenite-type zeolites were prepared via hydrothermal method using silica gel and sodium aluminate as Si and Al sources respectively. The temperature was varied from 150 °C up to 190 °C to determine the minimum temperature to obtain crystalline mordenite using a 23 mL Teflon-lined stainless-steel autoclave. The samples were characterized using XRD, FTIR and SEM. With the given experimental conditions, mordenite-type zeolites with good crystallinity and excellent purity were produced at 190 °C. Amorphous materials with notable peaks that correspond to mordenite planes were produced at 170 °C. The sample produced at 150°C was completely amorphous. FTIR revealed that all the three samples contain bands associated to aluminosilicate vibrational groups. However, a significant decrease in the intensities of vibration bands associated to hydroxyl (HO-) stretching and water bending were observed as the temperature is decreased. From the SEM, the sample treated at 190°C was composed of particles with strikingly linear edges having an average grain size of ∼38.0 μm. Most particles are hexagonal in shape. Particle components of the samples synthesized at 170 °C and 150 °C have irregular sizes and shapes.